r17928: Implement the basic store for CLDAP sitename

support when looking up DC's. On every CLDAP
call store the returned client sitename (if
present, delete store if not) in gencache with
infinate timeout. On AD DNS DC lookup, try looking
for sitename DC's first, only try generic if
sitename DNS lookup failed.
I still haven't figured out yet how to ensure
we fetch the sitename with a CLDAP query before
doing the generic DC list lookup. This code is
difficult to understand. I'll do some experiments
and backtraces tomorrow to try and work out where
to force a CLDAP site query first.
Jeremy.
(This used to be commit ab3f0c5b1e9c5fd192c5514cbe9451b938f9cd5d)

1 files changed, 94 insertions, 5 deletions

diff --git a/source3/libads/dns.c b/source3/libads/dns.c
index 8cc68a0c14..937cd9213f 100644
--- a/source3/libads/dns.c
+++ b/source3/libads/dns.c
@@ -565,16 +565,105 @@ NTSTATUS ads_dns_lookup_ns( TALLOC_CTX *ctx, const char *dnsdomain, struct dns_r
 	return NT_STATUS_OK;
 }
 
+/****************************************************************************
+ Store and fetch the AD client sitename.
+****************************************************************************/
 
-/********************************************************************
-********************************************************************/
+#define SITENAME_KEY	"AD_SITENAME"
+
+/****************************************************************************
+ Store the AD client sitename.
+ We store indefinately as every new CLDAP query will re-write this.
+****************************************************************************/
 
-NTSTATUS ads_dns_query_dcs( TALLOC_CTX *ctx, const char *domain, struct dns_rr_srv **dclist, int *numdcs )
+BOOL sitename_store(const char *sitename)
 {
-	pstring name;
+	time_t expire;
+	BOOL ret = False;
+	
+	if ( !sitename || (sitename && !*sitename)) {
+		DEBUG(2,("sitename_store: deleting empty sitename!\n"));
+		return gencache_del(SITENAME_KEY);
+	}
+	
+	if (!gencache_init()) {
+		return False;
+	}
+	
+	expire = get_time_t_max(); /* Store indefinately. */
+	
+	DEBUG(10,("sitename_store: sitename = [%s], expire = [%u]\n",
+		sitename, (unsigned int)expire ));
+
+	ret = gencache_set( SITENAME_KEY, sitename, expire );
+	return ret;
+}
 
-	snprintf( name, sizeof(name), "_ldap._tcp.dc._msdcs.%s", domain );
+/****************************************************************************
+ Fetch the AD client sitename.
+ Caller must free.
+****************************************************************************/
 
+static char *sitename_fetch(void)
+{
+	char *sitename = NULL;
+	time_t timeout;
+	BOOL ret = False;
+	
+	if (!gencache_init()) {
+		return False;
+	}
+	
+	ret = gencache_get( SITENAME_KEY, &sitename, &timeout );
+	if ( !ret ) {
+		DEBUG(5,("sitename_fetch: No stored sitename\n"));
+	} else {
+		DEBUG(5,("sitename_fetch: Returning sitename \"%s\"\n",
+			sitename ));
+	}
+	return sitename;
+}
+
+/********************************************************************
+ Query with optional sitename.
+********************************************************************/
+
+NTSTATUS ads_dns_query_dcs_internal(TALLOC_CTX *ctx,
+				const char *domain,
+				const char *sitename,
+				struct dns_rr_srv **dclist,
+				int *numdcs )
+{
+	char *name;
+	if (sitename) {
+		name = talloc_asprintf(ctx, "_ldap._tcp.%s._sites.dc._msdcs.%s",
+				sitename, domain );
+	} else {
+		name = talloc_asprintf(ctx, "_ldap._tcp.dc._msdcs.%s", domain );
+	}
+	if (!name) {
+		return NT_STATUS_NO_MEMORY;
+	}
 	return ads_dns_lookup_srv( ctx, name, dclist, numdcs );
 }
 
+/********************************************************************
+ Query for AD DC's. Transparently use sitename.
+********************************************************************/
+
+NTSTATUS ads_dns_query_dcs(TALLOC_CTX *ctx,
+			const char *domain,
+			struct dns_rr_srv **dclist,
+			int *numdcs )
+{
+	NTSTATUS status;
+	char *sitename = sitename_fetch();
+
+	status = ads_dns_query_dcs_internal(ctx, domain, sitename, dclist, numdcs);
+	if (sitename && !NT_STATUS_IS_OK(status)) {
+		/* Sitename DNS query may have failed. Try without. */
+		status = ads_dns_query_dcs_internal(ctx, domain, NULL, dclist, numdcs);
+	}
+	SAFE_FREE(sitename);
+	return status;
+}